Many portable electronic devices, for example, a note type personal computer, a PDA (Personal Digital Assistant), a portable telephone, a digital still camera, a digital video camera, and a music player use a rechargeable battery pack (hereinafter simply referred to as a battery) as a power supply.
If a battery attached to such a portable electronic device has a defect, there may be a problem such that the portable electronic device cannot fully function with its designed performance. Thus, it is preferred that the use of such a battery be restricted. A battery that has a defect denotes that it is defective or it is a counterfeit.
Although there is a battery that has a built-in memory that stores information about the user, if an illegal charger is used, it is supposed that such information is illegally read therefrom. Thus, it is preferred that the use of an unauthorized charger, namely an illegal charger, be restricted.
As methods of suppressing the use of a battery having a defect or an illegal charger, a method of which a battery having a defect is not recharged (for example, refer to Japanese Patent Application Laid-Open No. 2005-321983), a method of which an illegal charger is detected on a battery side (for example, refer to Japanese Patent Application Laid-Open No. 2004-310387), and a method of which an authenticating process is performed between a battery and a portable electronic device or a charger have been proposed.
There are batteries that detect their states such as current, voltage, and temperature, calculate their remaining capacity based on the detected results, control charging and discharging based on the calculated remaining capacity, and inform the electronic device side of these information.
FIG. 1 shows an exemplary structure especially of a connected portion of a note type personal computer (hereinafter, referred to as a note type PC) and a battery that is a power supply of the note type PC and that can inform the note type PC of the foregoing information about the battery.
The note type PC 10 not only uses the battery 20 as a power supply, but receives power from a power line (not shown) and functions as a charger for the battery 20.
A controlling MCU (Micro Control Unit) 11 is disposed on a substrate of the note type PC 10. The controlling MCU 11 has a built-in memory 12 that stores a control program and a built-in I/O port 13. By executing the control program, a charging controlling section 14, a battery state checking section 15, and a display controlling section 16 are accomplished as functional blocks.
The charging controlling section 14 controls a charging process for the battery 20 that is attached to the note type PC 10. The battery state checking section 15 obtains information (eg, current, voltage, temperature, remaining capacity) that represents the state detected from the battery 20. The display controlling section 16 controls indications for the user such as remaining capacity of the battery 20 based on the obtained information that represents the state of the battery 20.
A controlling MCU 21 is disposed on a substrate of the battery 20. The controlling MCU 21 has a built-in memory 22 that stores a control program and a built-in I/O port 23. By executing the control program, a charging/discharging controlling section 24 and a battery state detecting section 25 are accomplished as functional blocks.
The charging/discharging controlling section 24 controls charging and discharging of the battery 20. The battery state detecting section 25 detects the state (eg, current, voltage, temperature, remaining capacity) of the battery 20.
To cause the exemplary structure shown in FIG. 1 to execute an authenticating process of suppressing the use of a battery having a defect and preventing a normal battery from being attached to an illegal note type PC, there are a software extending method and a hardware extending method.
Specifically, the software extending method is a method of adding an authenticating process to the control program of the controlling MCU 11 and the control program of the controlling MCU 21.
If the software extending method is used, authentication information is communicated between I/O ports 13 and 23 that are existing communication paths. Thus, it is likely that communication throughput between the I/O ports 13 and 23 decreases and that authentication information is read from the I/O ports 13 and 23 that are general purpose ports. In addition to an increase of the control program, there is another problem of which the loads applied on the control MCUs 11 and 21 increase.
On the other hand, the hardware extending method is, for example, as shown in FIG. 2, a method of disposing an authenticating section 32 on the substrate of the note type PC 10, connecting the authenticating section 32 and the controlling MCU 11, disposing an authenticating section 42 in the battery 20, and connecting the authenticating section 42 and the controlling MCU 21. More specifically, the hardware extending method is a method of connecting an I/O port 31 added to the controlling MCU 11 and an I/O port 33 built in the authenticating section 32, connecting an I/O port 41 added to the controlling MCU 21 and an I/O port 43 built in the authenticating section 42, and communicating authentication information between the authenticating section 32 and the authenticating section 42 through the I/O ports 33, 31, 13, 23, 41, and 43.
Next, with reference to a flow chart shown in FIG. 3, the authenticating process of the system shown in FIG. 2 will be described. In addition, in the following description, it is assumed that the master of the authenticating process and the slave of the authentication process are assigned to the note type PC 10 and the battery 20, respectively. Instead, the roles of the master and slave may be reversed.
The authenticating process is triggered, for example, when the battery 20 is attached to the note type PC 10, when the power of the note type PC 10 to which the battery 20 has been attached is turned on or off, or when the operation, for example, of a predetermined button is detected.
At step S1, the controlling MCU 11 of the note type PC 10 outputs an authentication start command to the controlling MCU 21 of the battery 20. At step S2, corresponding to the command, the controlling MCU 21 outputs a resume (startup) command to the authenticating section 42 that is in a standby state for power saving. Corresponding to this command, the authenticating section 42 resumes (starts up).
At step S3, the controlling MCU 11 outputs a resume (startup) command to the authenticating section 32 that is in a standby state for power saving. Corresponding to this command, the authenticating section 32 resumes (starts up). At step S4, the controlling MCU 11 outputs an authentication start command to the authenticating section 32 that has resumed (started up).
At step S5, corresponding to this command, the authenticating section 32 outputs first question information against the authenticating section 42 of the battery 20 to the controlling MCU 11 through the I/O port 33. At step S6, the controlling MCU 11 outputs the first question information that has been input through the I/O port 31 to the controlling MCU 21 of the battery 20 through the I/O port 13. At step S7, the controlling MCU 21 outputs the first question information that has been input through the I/O port 23 to the authenticating section 42 through the I/O port 41.
At step S8, the authenticating section 42 generates first response information against the first question information that has been input through the I/O port 43 and outputs the generated first response information to the controlling MCU 21 through the I/O port 43. At step S9, the controlling MCU 21 outputs the first response information that has been input through the I/O port 41 to the controlling MCU 11 of the note type PC 10 through the I/O port 23. At step S10, the controlling MCU 11 outputs the first response information that has been input through the I/O port 13 to the authenticating section 32 through the I/O port 31.
In addition, when the question information and the response information are relayed, if necessary, in the controlling MCUs 11 and 21, data formats of these information are converted for the individual I/O ports.
Thereafter, the same processes as steps S5 to S10 are repeated a predetermined number of time, N−1. As the processes from steps S11 to S16, N-th question information is transmitted from the authenticating section 32. N-th response information corresponding to the N-th question information is returned to the authenticating section 32. The authenticating section 32 determines whether or not the battery 20 is an authorized battery based on the first to N-th response information.
At step S17, the controlling MCU 21 that has output the N-th response information to the controlling MCU 11 of the note type PC 10 as the process at step S15 outputs a standby command to the authenticating section 42. Corresponding to this command, the authenticating section 42 becomes the standby state again.
At step S18, the authenticating section 32 of the note type PC 10 outputs an authenticated result that denotes whether the battery 20 is an authorized battery or an unauthorized battery or whether or not a communication error has occurred to the controlling MCU 11. Based on the authenticated result, the controlling MCU 11 causes the charging controlling section 14 to stop the charging process or the display controlling section 16 to inform the user that the battery 20 is for example a defective battery.
Thereafter, at step S19, the controlling MCU 11 outputs the standby command to the authenticating section 32. Corresponding to this command, the authenticating section 32 becomes the standby state again. Now, the authenticating process is complete.
As described above, if the hardware extending method is used, like the case that the software extending method is used, authentication information is communicated between the I/O ports 13 and 23 that are existing communication paths. Thus, communication throughput decreases between the I/O ports 13 and 23. In addition, it is likely that authentication information is read from the I/O ports 13 and 23 that are general purpose ports.
In addition, since the communication path for authentication information (question information and response information) is lengthened, the communication time is proportionally prolonged. In addition, whenever authentication information is relayed, the format of the data needs to be converted for each I/O port. Thus, the loads applied on the controlling MCUs 11 and 21 increase.
Since a controlling MCU for a portable electronic device and a controlling MCU for a battery normally do not have affordable processing capacity due to cost reduction, it is recommended that the controlling MCUs be more simplified and load applied thereon be reduced.